1. Field of the Invention
The present invention relates to a wiper arm of a vehicle windshield wiper.
2. Description of the Related Art
A wiper arm has an arm head fixed to a pivot mounted on a portion of a vehicle body at one end and a retainer at the other end thereof. The retainer is rotatably connected to the arm head to move close to or apart from the surface of windshield in a suitable angle. The retainer retains an arm piece at the tip thereof, and the arm piece holds a wiper blade. A coil spring is disposed between the arm head and the retainer to press the retainer toward the windshield. An end of the coil spring is fixed to the base portion of the arm piece. The wiper blade is composed of a rubber blade and a holder lever.
When the wiper operates, the wiper arm and wiper blade swing back and forth on the windshield to wipe off raindrops.
The retainer usually has a top wall and a pair of parallel walls extending from opposite sides of the top wall. Therefore, the retainer has a U-shaped cross section, and the open side of the retainer faces the windshield.
When the vehicle runs at a high speed and the retainer is put in high speed air flow, not only a big air-blowing sound but also dynamic lift are generated.
In order to prevent such problems, it has been proposed that the front side of the wall that is located at the upstream side of the retainer is inclined. However, in the wiper arm having such inclined front wall, the coil spring disposed between the front and rear walls become so close to the front wall that the coil member may interfere with the front wall. This causes another noise, and the spring may scratch coating of the retainer, thereby causing the retainer to rust.
Moreover, because the arm piece has to be fixed to the side of the top wall near the rear wall, an angular moment or torsion is generated relative to the longitudinal center line of the retainer by the spring, thereby resulting noises and unstable wiping.